Shows like the old Amanda show, more recently Late Night with Seth Meyers have segments where the camera/cue/etc crew members interact on screen. Do these members likely have special contracts/addendums to appear on screen? Are they actually actors? Would they likely need to be part of SAG?
To Join SAG, you must have done some previous work so showing random crew members on air should be allowed espically if it is a one off appearance.
From SAG website on what is needed to join:
Here's what you need to qualify:
Proof of Employment SAG-AFTRA membership is available to those who work in a position covered by a SAG-AFTRA (or AFTRA or SAG) collective bargaining agreement, provided that any person qualifying through work as a background actor must have completed three (3) days of work as a background actor under a SAG-AFTRA (or AFTRA or SAG) collective bargaining agreement. Membership is also available to those who work one (1) day of employment in a principal or speaking role (actor/performer), or as a Recording Artist in a SAG-AFTRA (or AFTRA or SAG) covered production.
Employment Under an Affiliated Performers' Union Performers may join SAG-AFTRA if the applicant is a paid-up member of an affiliated performers' union such as ACTRA, AEA, AGMA or AGVA for a period of one year, and has worked and been paid for at least once as a principal performer in that union’s jurisdiction.
I think this happens based on the script writers where they develop segments to involve and engage the crew members. They are obviously aware of this ahead of taping.
I am not sure it constitutes as them becoming an actor and being part of a union such as SAG or any others.
For example, Andy (The producer of Ellen's show) is credited as the executive producer even on the IMDB page. He has no acting credits despite have active segments on the show. I believe if you work part of the crew you can also act (for example, stand-ins, stunt crew, etc who appear on screen do not get the acting credits but are listed at the title credits at the end under the respective category).
At the end of the day your title of the job takes the credit. This is from what I can gather.
Roles and Responsibilities here